1. Field of Invention
The present disclosure relates in general to a tool for regulating fluid flow through a perforating string. The present disclosure relates more specifically to a pressure activated tool for selectively directing a flow of connate fluid in the perforating string, and which includes indexing and switching assemblies.
2. Description of Prior Art
Perforating systems are used for the purpose, among others, of making hydraulic communication passages, called perforations, in wellbores drilled through earth formations so that predetermined zones of the earth formations can be hydraulically connected to the wellbore. Perforations are needed because wellbores are typically completed by coaxially inserting a pipe or casing into the wellbore. The casing is retained in the wellbore by pumping cement into the annular space between the wellbore and the casing. The cemented casing is provided in the wellbore for the specific purpose of hydraulically isolating from each other the various earth formations penetrated by the wellbore.
Perforating systems typically include one or more perforating guns strung together, these strings of guns can sometimes surpass a thousand feet of perforating length. Gun strings are generally deployed on wireline or slick line, and on tubing when the mass of the gun string exceeds the wireline/slick line handling capability. Some downhole configurations have the perforating string deployed downhole with a packer at a location around the string to define a pressure/flow barrier in the annulus between the string and borehole wall. Sometimes a need exists to selectively divert a flow of fluid within the perforating string to surface, or to circulate fluid within the annular space above the packer.